CVE-2026-53704: Gstreamer1-plugins-ugly-free: gstreamer: out-of-bounds read in realmedia demuxer fileinfo metadata parser

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-15 · updated 2026-09-08
Weakness: CWE-125

Description

A flaw was found in GStreamer's RealMedia demuxer in the gst-plugins-ugly package. When processing a RealMedia file containing a specially crafted FILEINFO metadata section, the demuxer parses variable-name and variable-value pairs using re_skip_pascal_string() without validating that offsets remain within the mapped buffer. Additionally, the element count controlling the parsing loop is read from attacker-controlled data without validation, which can cause an infinite loop. A crafted RealMedia file can cause the application to crash, hang, or potentially read limited adjacent memory contents.

Affected products

Red Hat Enterprise Linux 10: all versions — fixed in 0:1.26.7-2.el10_2.1
Red Hat Enterprise Linux 10.0 Extended Update Support: all versions — fixed in 0:1.24.11-1.el10_0.2
Red Hat Enterprise Linux 9: all versions — fixed in 0:1.22.12-6.el9_8.1
Red Hat Enterprise Linux 9.6 Extended Update Support: all versions — fixed in 0:1.22.12-4.el9_6.1

How to fix

Upgrade to a fixed version: Red Hat Enterprise Linux 10 0:1.26.7-2.el10_2.1; Red Hat Enterprise Linux 10.0 Extended Update Support 0:1.24.11-1.el10_0.2; Red Hat Enterprise Linux 9 0:1.22.12-6.el9_8.1; Red Hat Enterprise Linux 9.6 Extended Update Support 0:1.22.12-4.el9_6.1. Check the vendor advisory for mitigations.

References

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